1. Field of the Invention
The present invention relates to a transportable apparatus for intimately combining a waste material with a stabilizer material. More specifically, the present invention relates to a transportable apparatus which incorporates a plow blender for intimately combining a waste material with a stabilizer material. The present invention also relates to a transportable accessory for use with a plow blender for intimately combining a waste material with a stabilizer material.
2. Description of the Prior Art
There is a great need for stabilizing waste materials to make them relatively innocuous to the environment prior to their ultimate disposal. Such waste materials include sludges resulting from the processing of human and animal wastes, for example, sewage and agricultural sludges and manures. Such waste materials also include small particulate mining and industrial waste products which are often stockpiled or are deposited as slurries in storage ponds or lagoons.
A common characteristic of such waste materials is that they are unstable in a biological or chemical sense to a degree that disposal of these waste materials in an untreated form poses hazards to the environment. For example, untreated sewage sludge contains biologically active pathogens along with heavy metal contaminants, the exposure to any of which may endanger the health of human, animal, or plant life. Such exposure may result from direct contact with the waste material or indirectly through the leaching of contaminants from the waste material into water supplies from runoff into streams, rivers, lakes, and reservoirs, or through see page into the water table.
Another common characteristic of such waste materials is that they are finely-divided, particulate, or sludge-like in physical form. The physical form of these waste materials, therefore, enhances their instability. It also increases their ability to escape from containment structures and to migrate to where they might cause the most damage to the environment.
It has long been known that combining such waste materials with a stabilizer material can render the waste materials more stable or otherwise more innocuous to the environment, thereby reducing the potential environmental hazards associated with the ultimate disposal of such waste materials. A characteristic of effective stabilizer materials is that they have a physical form amenable to permitting intimate combination with waste materials. Thus, suitable stabilizer materials must be of a finely-divided, particulate, or sludge-like physical form. Another characteristic of such stabilizing materials is the ability to physically, chemically, or biologically interact with waste materials in such a way as to render the waste materials more stable or otherwise more innocuous to the environment. Calcium-rich or magnesium-rich powders, especially those containing oxides and hydroxides of these alkaline earth elements, such as lime, lime kiln dust, cement kiln dust, fly ash, slag fines, and pulverized calcium carbonate are illustrative examples of such stabilizing materials. For example, Nicholson, U.S. Pat. No. 4,554,002, teaches that mixing lime kiln dusts with sewage sludge reduces the pathogens and decreases the leachability of the heavy metal contaminants contained in the sewage sludge such that the resulting product may be used as a fertilizer.
The plow bender as described by Wurtz, U.S. Pat. No. 3,941,357, has been found to be a particularly effective device for combining waste materials with stabilizer materials. A plow blender is a dual shaft mixer capable of mixing all types of materials from dry to semi-solid to viscous liquids providing uniform shear, uniform work input and uniform particle temperature. Attached to each of the plow blender's two counter-rotating shafts are plow-shaped, double-wedge working tools. The dual shafts and the attached working tools are so arranged that the paths of the working tools on the two shafts overlap and so that the working tools mounted on one shaft coming in proximity to the shaft of the second set of working tools, and vice versa, thus creating zones of interaction between the sets of working tools.
Materials fed into the plow blender are intimately combined by the action of the working tools as the materials are worked through the plow blender and then discharged. Thus, the plow blender is capable of intimately combining the waste materials with stabilizer materials thoroughly and homogeneously. Additionally, the plow blender is capable of bringing waste materials and stabilizer materials into intimate contact thereby producing an intimate combination of these materials and thus enhancing the ability of the stabilizer material to render the waste material more innocuous to the environment.
The utility of the plow blender has been recognized for intimately combining some waste materials with some stabilizer materials. For example, Wurtz, U.S. Pat. No. 4,306,978, describes the use of the plow blender for intimately combining lime with sewage sludge to destroy pathogenic organisms resident in the sewage sludge.
Previously, however, the use of a plow blender has required the investment in costly physical plant facilities, such as the expense of purchasing and maintaining dedicated equipment such as the plow blender, and the storage equipment for the waste materials and the stabilizer materials at each waste material processing facility. It also has been necessary to dedicate a significant amount of the floor space of the facility to the waste material processing equipment and its operation. The associated costs and the limited amount of floor space at existing waste producing sites, especially at the older municipal sewage treatment plants and small factories, made it difficult or expensive to utilize this technology for rendering the waste materials produced at these sites less harmful to the environment. In addition the disposal of the untreated waste material, for example, by disposal into landfills, is expensive and potentially hazardous to the environment.
Furthermore, the need for the use of a permanent structure to house and operate the equipment greatly discourages the use of this technology for stabilizing waste materials on-site at land fills or at remote mining sites. The costs associated with such a permanent structure makes employing this technology to process waste materials economically unattractive to the owners of smaller industrial plants, mining operations, and farms.
Furthermore, some waste material producers may already have a plow blender which could be more effectively utilized if it could be used at more than one location. Presently, however, it was necessary for these waste material producers either to transport all the waste materials to a central location or to deinstall, move, and reinstall the plow blender at each location and to maintain dedicated supplemental equipment at each location for use with the plow blender.
What is lacking in the art, therefore, is a transportable, self-contained unit for intimately combining waste materials with stabilizer materials that can be employed at a waste producing site on an as-needed basis without requiring the permanent dedication of floor space. What is needed is a self-contained unit for intimately combining waste materials with stabilizer materials that can be moved from one waste producing site to another thus making it possible to spread the cost associated with the equipment among many users. What is needed is a self-contained unit for intimately combining waste materials with stabilizer materials that is adapted to be easily moved from one place to another, for example, from one land fill cell to another, from one farm to another, from one industrial plant to another, from one remote mining site to another, from a land fill to a farm, from a farm to an industrial plant, and so on. What is needed is a self-contained, transportable unit in which the plow blender can be mounted which has ancillary equipment necessary for the operation of the plow blender. What is needed is a transportable accessory to a plow blender which has reservoirs for receiving, containing, and discharging the waste materials and the stabilizer materials into the plow blender, as well as a means for controlling the discharges of these reservoirs.